Devices, particularly electronic devices, are becoming smaller, faster, and generally more difficult to design and debug at the system level.
One of the signaling techniques used for high speed circuits is that of using differential signals.
To achieve performance levels and immunity from interference, differential signals are commonly used in high-speed interfaces.
Many of the failure causes in a communications link result from a poorly positioned cross-point. Errors can develop in both the signal level (voltage) of the cross-point, or in the relative timing of the cross-point. This may present a problem.
Sensing the cross-point of a high-speed differential signal today requires the use of oscilloscopes and other expensive test equipment. Set up is difficult, since any connection of equipment to a high-speed signal causes alteration of the waveform and potentially complete obscuration of the parameter under measurement. It is frequently impossible to view a critical signal buried deep within a large functioning system. Any time a user must utilize an oscilloscope to monitor a signal; it becomes an expensive, time consuming process. Sometimes the results are marginal. This may present a problem.